technical solutions for discriminating tuna by species and size
The tuna fishing vessels are all well equipped with electronic fish detection instruments. However, these instruments can not (yet) make a good estimate of the size and species (in case mixed) of the tuna detected.
It will be crucial to get to the point where the fishermen know upfront if there are non-targeted species – and to which extend – into his upcoming set.
It will also be beneficial for the fishermen to know what catch composition he might expect.
This knowledge is mainly applicable for FAD fishing, where the quality of the buoys on the FAD plays an important role. Less FAD’s justify better electronic equipped buoys to estimate the volume and % of each species present with their size.
It is good for the tuna stocks, due to more selective fishing. It is also beneficial for the environment with less useless steaming of the tuna purse seiners.
Each skipper of a boat prefers the biggest net possible, but for selective fishing, it can be better to use a net which is less deep and with bigger meshes then currently used. Together with better studies on the behaviour of tuna, adaptable design of a tuna purse seine net for specific periods of the year can be feasible.